Magnesium dischloride-alcohol adducts and catalyst components obtained therefrom

Abstract

The present invention relates to MgCl 2 .mROH.nH 2 O adducts, where R is a C 1 -C 10 alkyl, 2≦m≦4.2, 0≦n≦0.7, characterized by an X-ray diffraction spectrum in which, in the range of 2θ diffraction angles between 5° and 15°, the three main diffraction lines are present at diffraction angles 2θ of 8.8±0.2°, 9.4±0.2° and 9.8±0.2°, the most intense diffraction lines being the one at 2θ=8.8±0.2°, the intensity of the other two diffraction lines being at least 0.2 times the intensity of the most intense diffraction line. Catalyst components obtained from the adducts of the present invention are capable to give catalysts for the polymerization of olefins characterized by enhanced activity and stereospecificity with respect to the catalysts prepared from the adducts of the prior art.

What is claimed is: 
     
       1. A MgCl 2 .mROH.nH 2  O adduct, where R is a C 1  -C 10  alkyl, 2≦m≦4.2, and 0≦n≦0.7, characterized by a X-ray diffraction spectrum in which in the range of 2θ diffraction angles between 5° and 15° three diffraction lines are present at diffraction angles 2θ of 8.8±0.2°, 9.4±0.2° and 9.8±0.2°, the most intense diffraction line being the one at 2θ=8.8±0.2°, the intensity of the other two diffraction lines being at least 0.2 times the intensity of the most intense diffraction lines. 
     
     
       2. An adduct according to claim 1, wherein 2.2≦m≦3.8, and 0.01≦n≦0.6 and R is a C 1  -C 4  alkyl. 
     
     
       3. An adduct according to claim 2, wherein R is ethyl. 
     
     
       4. An adduct according to claim 3, wherein the intensity of the diffraction lines at 2θ=9.4°±0.2° and 9.8°±0.2° is at least 0.4 times the intensity of the most intense diffraction line. 
     
     
       5. An adduct according to claim 4, wherein the intensity of the diffraction lines at 2θ=9.4°±0.2° and 9.8°±0.2° is at least 0.5 times the intensity of the most intense diffraction line. 
     
     
       6. An adduct according to claim 3, characterized by a Differential Scanning Calorimetry (DSC) profile in which no peaks are present at temperatures below 90° C. or, if peaks are present below said temperature, the fusion enthalpy associated with said peaks is less than 30% of the total fusion enthalpy. 
     
     
       7. An adduct according to claim 6 which is further characterized by a viscosity value at 125° C. which lies, on a plot viscosity vs. EtOH molar content, above the straight line passing through the points having, respectively, a viscosity expressed in poise and a EtOH molar content of 1.2/2.38 and 0.63/3.31. 
     
     
       8. An adduct according to claim 6, wherein the three diffraction lines at 2θ=8.8°±0.2°, 9.4°±0.2° and 9.8°±0.2° are the three main diffraction lines in the range of 2θ diffraction angles between 5° and 15°. 
     
     
       9. An adduct according to claim 6, wherein if peaks in the Differential Scanning Calorimetry (DSC) profile are present at temperatures below 90° C., the fusion enthalpy associated with said peaks is less than 10% of the total fusion enthalpy, and wherein the maximum peak occurs at temperatures between 95 and 115° C. 
     
     
       10. An adduct according to claim 1, in the form of spherical particles. 
     
     
       11. A catalyst component for the polymerization of olefins comprising the product of the reaction between a transition metal compound and an adduct according to claim 1. 
     
     
       12. A catalyst component for the polymerization of olefins comprising the product of the reaction between a transition metal compound and a MgCl 2  -alcohol adduct, said adduct being obtainable by partially dealcoholating an adduct according to claim 1. 
     
     
       13. A catalyst component for the polymerization of olefins according to claim 12 in which the partially dealcoholated adduct contains from 0.1 to 2.6 moles of alcohol per mole of MgCl 2 . 
     
     
       14. A catalyst component for the polymerization of olefins according to claim 11 in which the transition metal compound is a titanium compound of formula Ti(OR) n  X y-n  in which n is between 0 and y; y is the valency of titanium; X is halogen and R is an alkyl radical having 1-8 carbon atoms or a COR group. 
     
     
       15. A catalyst component for the polymerization of olefins according to claim 14 in which the transition metal compound is a titanium compound having at least one Ti-halogen bond. 
     
     
       16. A catalyst component for the polymerization of olefins according to claim 15, wherein the titanium compound is titanium tetrahalides or halogenalcoholates. 
     
     
       17. A catalyst component for the polymerization of olefins according to claim 15 comprising an electron donor compound. 
     
     
       18. A catalyst component for the polymerization of olefins according to claim 17 in which the electron donor compound is selected from the group consisting of esters, ethers, amines, silanes and ketones. 
     
     
       19. A catalyst component for the polymerization of olefins according to claim 18 in which the electron donor compound is selected from the group consisting of alkyl and aryl esters of mono and polycarboxylic acids. 
     
     
       20. Catalyst for the polymerization of olefins comprising the product of the reaction between a catalyst component according to claim 11, and an aluminum alkyl compound. 
     
     
       21. Catalyst for the polymerization of olefins according to claim 20 in which the aluminum compound is a Al-trialkyl compound. 
     
     
       22. Catalyst for the polymerization of olefins according to claim 20 further comprising an external donor. 
     
     
       23. Catalyst for the polymerization of olefins according to claim 22 in which the external donor is selected from the group consisting of silane compounds containing at least a Si--OR link, having the formula R a   1  R b   2  Si(OR 3 ) c , where a and b are integer from 0 to 2, c is an integer from 1 to 3 and the sum (a+b+c) is 4; R 1 , R 2 , and R 3 , are alkyl, cycloalkyl or aryl radicals with 1-18 carbon atoms.